398 ZOOLOGY SECT. 



having been acquired by many Carinatse which have lost the 

 power of flight. The keel is very small in Ocydromus, Notornis, and 

 Aptornis, three flightless Rails the latter extinct from New 

 Zealand, and is practically absent in the Dodo (Didus) and Solitaire 

 (Pezopkaps), two gigantic extinct Pigeons from Mauritius and 

 Rodriguez, in the Kakapo or Ground-parrot (Stringops) of New 

 Zealand, in the extinct Giant-goose (Onemiornis) from the same 

 country, and in Hesperornis. The absence of the carina may 



FIG. 1002 is. Eudyptes pachyrhynchus (Penguin). Skeleton. (From a photograph 



by A. Hamilton.) 



therefore be considered as an adaptive modification of no signifi- 

 cance as indicating affinity. 



The entire order of Penguins (Impennes) and the extinct Great 

 Auk (Alca impennis) are also flightless, but their wings, instead of 

 being functionless, are modified into powerful swimming paddles 

 (Fig. 1002 bis). There has therefore, in these cases, been no re- 

 duction either of the pectoral muscles or of the carina. 



